Continuous charging apparatus

ABSTRACT

An apparatus for charging metal bodies into a coating pot constructed on a carousel-like carriage assembly having a plurality of feeding chutes in a circular arrangement at equally spaced intervals. Each chute is provided with a conveying unit for gradually lowering a metal body made up of several pigs or a single slab into a coating pot to maintain a constant molten metal level. Upon the pigs being consumed in one chute, the carriage assembly is automatically turned by a drive assembly to index the next successive chute with respect to the coating pot. This operation is repeated until all the chutes are empty.

Unite States Patent liillin et all.

[541 CUNTlNUOUS CHARGING APPARATUS [72] inventors: King D. Killin, Middletown; Ellis lll.

Lieungh, Miamisburg, both of Ohio [73] Assignee: Kaiser industries Corporation, Oakland,

Calif.

22 Filed: Sept. 25, 1970 [211 Appl.No.: 75,320

Field oiSearch ..1l8/7,429,8; 164/80, 87; 214/658, 1 B; 221/82 [56] References Cited UNITED STATES PATENTS 1,926,914 Popov ..l98/209 1 Mar. M, W72

2,111,730 3/1938 Rabens et al .,198l209 X 3,522,836 8/1970 King ..1 18/7 X Primary Examiner-Morris Kaplan Attorney-James E. Toomey, Paul E. 'Calrow, Harold L. Jenkins and John S. Rhoades {5 7] ABSTRACT An apparatus for charging metal bodies into a coating pot constructed on a carousel-like carriage assembly having a plurality of feeding chutes in a circular arrangement at equally spaced intervals. Each chute is provided with a conveying unit for gradually lowering a metal body made up of several pigs or a single slab into a coating pot to maintain a constant molten metal level. Upon the pigs being consumed in one chute, the carriage assembly is automatically turned by a drive assembly to index the next successive chute with respect to the coating pot. This operation is repeated until all the chutes are empty.

12 Claims, 10 Drawing Figures Patented March 14, 1972 4 Sheets-Sheet :1

KING D. KILL/1v w 6 1.1.15 H. L/fiUA/GH Pammed March 14, 1972 3,648,655

4 Sheets-Sheet 4 [Fave D. KILL/IV? 14 16 H. Llsuugv AT ENE? CONTINUOUS CHARGING APPARATUS BACKGROUND OF THE INVENTION This invention relates to an apparatus for feeding metal bodies to a metallurgical operation, and more particularly to an apparatus for charging metal bodies into a coating pot or the like.

The conventional manner of charging a coating pot used with a coating line is accomplished by hand or a pig feeder designed to handle small pigs of about 50 pounds. In those lines requiring frequent charging, normally by way of a slab, the current practice is to use a manually operated monorail hoist positioned over the coating pot.

This invention is intended to avoid the necessity of manually charging a slab to a coating pot or utilization of a conventional pig feeder thereby effecting a savings on the cost of material and in manpower cost. Furthermore, this invention is designed to automatically feed a plurality of metal bodies in successive order over a long period of time.

SUMMARY OF THE INVENTION The charging apparatus of this invention comprises a rotatably mounted carriage assembly having a plurality of feeding chutes which carry conveying units for metal bodies, and a drive assembly that sequentially indexes the feeding chutes in alignment with a coating pot. Once a chute is aligned with a coating pot, its conveying unit gradually lowers the metal bodies into the molten bath a sufficient distance to maintain a selected bath level.

The conveying unit for each chute includes a holding device that is adapted to ride up and down a ramp whose lower end is disposed above the coating pot. The holding device is moved by a hoist drive mechanism and has several lock levers connected in tandem to releasably clamp the upper end of one or more metal slabs or pigs. When there is only a remainder of the slabs left, the rotation of the hoist drive mechanism is reversed to raise the pig conveying unit, and as it raises, a trip lever mounted on the feeding chute strikes a dump bar carried by the pig holding device to release the several lock levers in unison. The drive assembly for turning the carriage assembly is then automatically actuated indexing the entire carriage assembly through an angle to place the next chute in position and the charging operation is repeated.

DESCRIPTION OF THE DRAWINGS For a better understanding of this invention, reference may be made to the accompanying drawings, in which:

FIG. 1 is an elevational view of the preferred embodiment of this invention, illustrated adjacent to a coating line station;

FIG. 2 is a top plan view of the preferred embodiment depicted in FIG. I;

FIG. 3 is an enlarged partial view of FIG. I showing in solid lines the conveying unit for one of the chutes holding a pig in the upper start position and showing in dotted lines the conveying unit holding a pig in the lower release position;

FIG. 4 is a front view of the holding device illustrated as holding a plurality of pigs;

FIG. Sis a top view of FIG. 4;

FIG. 6 is a partial side view of the holding device of FIGS. 4 and FIG. 7 is a partial front view of a lock lever which forms a part of the holding device of FIGS. 4, 5 and 6;

FIG. 8 is a partial rear view of the lock lever of FIG. 7 de picted in locking engagement with a pig;

FIG. 9 is a partial enlarged view of FIG. 3 illustrating a trip lever carried by a chute engaging a dump bar as the conveying unit is being raised; and

FIG. 10 is identical with FIG. 9 showing the dump bar rotated by the trip bar to free the pigs from the holding device.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. I and 2, there is illustrated a charging apparatus generally designated by the reference numeral 116 and embodying the principles of this invention. The charging apparatus 10 is positioned adjacent to a coating line station 12, which is disposed along and forms a part of a continuous coating line for applying a metal film, such as zinc or aluminum, to a continuous strip of metal S, such as steel.

The coating line station 12 includes a circular coating pot 14. The coating pot 14 is supported in a deep well formed along and below the operating level of the coating line, and contains a volume of molten metal M. The continuous strip of metal S is directed through a chamber or hood 16 by means of a series of guide rollers 18. The strip of metal S exists from the lower open end of the vertical leg of hood 16 into the molten metal M, and an immersed pot rig roll assembly 20 directs the strip of metal S through the molten metal M and upwardly towards the next station in the coating line process.

The charging apparatus I0 is constructed on a carriage assembly 2ll having a radial framework 22, which is adaptable to turn through a complete circle. The support for radial framework 22 is provided by a pedestal 24 and vertical column 26 which extends upwardly from pedestal 24 through the center of cylindrical shell 27 of framework 22. The radial framework 22 is rotatably supported at its lower and upper ends, respectively, to pedestal 24 and vertical column 26 by means of bearings 25 and 29. Bearing 29 is a roller bearing disposed about bushing 31, which is secured to the reduced diameter portion 33 of vertical column 26. Integrally formed with the upper and lower ends, respectively, of shell 27 are upper and lower octagonal horizontal bases 28 and 30. The upper and lower octagonal bases 28 and 30 are rigidly braced by the cylindrical shell 27 by means of a plurality of radial webs 32 and 34, respectively. Extending radially from the sides of the upper and lower octagonal bases 32 and 34 are a plurality of upper and lower horizontal support beams 36 and 38. A plurality of feeding chutes 40 are integrally supported by the outer ends of the upper and lower support beams 36 and 38 in a transverse angle to the vertical. The feeding chutes 40 are constructed as an elongated rectangular-shaped ramp 42 with two parallel upstanding guide rails 44 and 416.

The carriage assembly 21 for the charging apparatus 10 is turned by a drive assembly 48 to sequentially index the feeding chutes 40 in alignment with the coating pot I4. The drive assembly illustrated in FIG. 1 includes a motor 50, a gear box 52, a drive gear 54 and a driven gear 56 secured to the lower face of lower octagonal base 30. On. the lower face of the driven gear 56 is formed a circular ball race 57 for ball bearing 25.

Each of the feeding chutes 40 is provided with a conveying unit 60 which can carry a plurality of pigs P or one very large slab. Since each conveying unit 60 is identical in construction for each of the eight chutes 40, only one will be described.

Referring to FIG. 1, the conveying unit 60 comprises a motor 62, a pulley 64, a hoist cable 66, and a clamp device 66. The motor 62, which could be any conventional electrical or hydraulic motor, is mounted on the upper octagonal base plate 28 and includes a winding drum for reeling and unreeling cable 66. Cable 66 extends from the motor 62 over the pulley 64 mounted at the outer end of upper support beam 36, and down the ramp 42. Cable 66 is fastened to clamp device 68 by using a hook 70.

The clamp device 68, illustrated in FIG. 4, is depicted holding nine pigs P at their upper ends. As depicted in FIG. 6, the pigs P have a trapezoidal cross section and are arranged in abutting side by side relation to provide, in effect, a large metal slab. The clamp device 68 has an elongated U-shaped frame 72 with its two arm portions 74 and 76 separated a distance slightly larger than the thickness of the pigs P in order to fit over the upper end of the pigs P.

The clamp device 68 includes a locking unit 78 for holding the pigs P in the U-shaped frame 72. The locking unit 76 has a plurality of cam-locked fingers 80 connected in tandem in a spaced relation along the length of U-shaped frame 72. At one end of each cam-locked finger 80 is an integrally formed cam 82 having a circular bore 84 formed perpendicular to its length for rotatably supporting the cam-locked finger 80 on an elongated circular pivot rod 86, which extends the length of the U-shaped frame 72. The pivot rod 86 is supported along the length of the U-shaped frame 72 by means of a plurality of clamps 87 which are fastened to the arm 76 of U-shaped frame 72 by a pair of bolts 88.

The cam 82 on the cam-locked finger 80 has a curved portion 90 which is adapted to project into the interior of the U- shaped frame 72 through a rectangular-shaped opening 92 formed in the arm 76. To provide a good grip on the pigs P, the curved portion 90 of each cam 82 is tapered outwardly to form a substantially pointed end 94, as illustrated in FIGS. and 7. Because the casted pigs are quite difficult to grip, it is preferable that the peripheral and pig or slab contacting surface of the curved portion 90 of a cam 82 is provided with a series of serrated or stepped edges 95 as indicated in FIGS. 67. By reason of the series of stepped edges 95 a surface portion of a pig P is usually marred in the manner generally indicated at 96 in FIGS. 4-5 upon rotation of a cam-locked finger 80, as will be subsequently described.

To operate the cam-locked fingers 80 in unison, their free ends 98 are secured to an elongated release bar 100 extending parallel to pivot rod 86. By pulling upwardly on release bar 100, the cam-locked fingers 80 rotate counterclockwise as viewed in FIG. 6 to release their grip on pigs P.

The unlocking of release bar 100 is effectuated by the cooperation between a pair of dump bars 102 and a pair of trip levers 104. The two trip levers 104 are pivotally mounted behind and on the outside of guide rails 44 and 46, and are spring biased (not shown) to pivot counterclockwise as viewed in FIG. 9. The two dump bars comprise two bell crank levers 106 pivotally connected on the opposite ends of pivot rod 86. One arm 108 of bell crank lever 106 is connected to release bar 100 and the other two arms 110 extend in the path of the pair of trip levers 104. By virtue of this arrangement, the arms 110 engage the outer free end of trip levers 104 as the clamp device 68 is lowered, causing the trip levers to pivot clockwise (as viewed in FIG. 9) out of contact with dump bars 102. Thereafter the trip levers 104 spring back until they strike stops 111 (FIG. 9). Trip levers 104 are engaged by the pair of arms 110 as the clamp device 68 is raised to actuate lock unit 78, releasing the remainder ofthe (9) pigs P.

The clamp device 68 includes a pair of transport wheels 114 which ride along the ramp 42 between the guide rails 44, 46. A centrally located lifting bracket 116 (FIG. 4) is provided on top of each clamp device 68 constructed as a pair of bifurcated ears 118, 120 with a bolt 122 extending therebetween for receiving hook 70. Equally spaced on either side of lifting bracket 116 are a pair of lifting lugs 124 which can be used in placing the clamping device 68 over the ends of pigs P to load the same.

In loading the charging apparatus 10, it is best to sequentially load each chute 40 at a station adjacent to the coating pot 14 and to sequentially turn the carriage assembly 21 through an angle equal to the angle separating the chutes 40 so that the first loaded chute is disposed in a feeding position directly over the coating pot 14 when the last chute is being loaded. Upon completion of the loading, the operator would actuate a start button to energize motor 62 in a direction to unwind cable 66 until the lower end of pigs P are immersed a sufficient distance in the molten bath M to raise its level to a predetermined height.

By virtue of a conventional electrical control circuit responsive to changes in the level of the molten bath M, the motor 62 for the chute 40 in the feeding position is periodically energized for short periods to lower the pigs P in discrete increments until the clamp device 68 passes over the trip lever 104 (see FIG. 3). When this event occurs, the trip lever 104 springs upwardly against stop 111 and actuates an electrical solenoid switch (not shown). The actuation of this solenoid switch initiates a signal in the control circuitry to cause the motor 62 to reverse its direction of rotation and start reeling in cable 66. Consequently, clamp device 68 and the remainder of the pigs P are raised up ramp 42, and during this upward movement, the arms of the pair of dump bars 106 engage and turn about the outer end of the pair of trip levers 104 (FIG. 10) to open the cam-lock fingers 80. The remainder of the pigs P fall into the molten bath M. The conveying unit 60 continues to raise until clamp device 68 strikes a limit switch (not shown) on chute 40 to provide a signal for stopping motor 62 and for energizing the drive assembly 48 to turn the carriage assembly until the next chute is indexed with respect to coating pot 14. The conveying unit for this next chute will now automatically be energized for lowering its clamp device and associated pigs into the molten bath M in the same manner. This charging process will continue until all eight chutes have been used.

By using the charging apparatus of this invention, it is possible to charge continuously up to 8 hours before reloading, or it is possible to continuously reload each of the chutes during the charging operation.

What is claimed is:

1. Apparatus for charging a metal body into a coating pot containing molten metal through which a substrate to be coated can be passed, said apparatus comprising a carriage assembly having at least one feeding chute, said feeding chute including a ramp extending transversely to the horizontal axis, means for moving said carriage assembly to position the lower end of said ramp above and adjacent to the coating pot, a clamp device adapted to ride up and down said ramp including a frame means for fitting over the edge of a metal body and lock means for releasably holding the metal body in said frame means, lever means carried by said frame means for opening said lock means to release the holding force on the metal body, and trip means carried by said chute and disposed in the path of said lever means for actuating said lever means to thereby open said lock means and release the holding force on the metal body, and means for raising and lowering said clamp device along the length of said ramp.

2. Apparatus as defined in claim 1, wherein said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of the metal body and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end along the length of one of said parallel arms in a spaced relation, said one end of said lock fingers having a curved portion adapted to project into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock fingers, said release bar coupled to said lever means for rotating said lock fingers in unison to an open position upon said lever means being actuated by said trip means.

3. Apparatus as defined in claim 1, wherein said chute includes two parallel guide rails extending along opposite sides of said ramp in a longitudinal direction, and wherein said clamp device includes two roller members separated a distance slightly less than the distance separating said guide rails and adapted to ride on said ramp between said guide rails.

4. Apparatus as defined in claim 1, wherein said trip means I comprises a pair of trip levers rotatably mounted at opposite sides of said ramp along its length and spring-biased upwardly so that the free ends of said trip levers are adapted to be rotated downwardly behind the surface of said ramp, and stop means to engage and hold said trip levers when their free ends rotate upwardly to a lever actuating position in front of said ramp, whereby said trip levers are rotated downwardly by engagement with said lever means as said clamp device is lowered and thereafter springs upwardly to said lever actuating position.

5. Apparatus as defined in claim 1, where said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of a metal body, a plurality of apertures formed in a straight line along the length of one of said parallel arms and a pivot rod fastened to the outside surface of said one parallel arm in a manner to extend across each of said plurality of apertures, and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end on said pivot rod in alignment with said plurality of apertures, said one end of said cam lock fingers having a curved portion adapted to project through said apertures into the interior of said U- shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock fingers, said release bar coupled to said lever means for rotating said cam lock fingers in unison to an open position upon said lever means being actuated by said trip means.

6. Apparatus as defined in claim 5, wherein said lever means comprises a pair of dump bars pivotally mounted on said pivot rod, said dump bars having a first arm secured to said release bar and a second arm disposed in the path of said trip means.

7. Apparatus for charging a metal body into a coating pot containing molten metal through which a substrate to be coated is passed, said apparatus comprising a carriage assembly and a drive assembly, said carriage assembly comprising a radial framework forming a plurality of equally spaced chutes in a circular arrangement, each of said chutes including a ramp extending transversely to the horizontal axis, base means for rotatably supporting said radial framework such that the lower end of said ramps can be positioned above and adjacent to the coating pot, each of said chutes having a clamp device adapted to ride up and down said ramp and means for raising and lowering said clamp device along the length of said ramp, said clamp devices including frame means for fitting over the edge of a metal ingot and lock means for releasably holding the metal ingot in said frame means, lever means carried by said frame means for opening said lock means to release the holding force on the metal body trip means carried by each of said ramps and disposed in the path of said lever means for actuating said lever means to thereby open said lock means and release the holding force on the metal body, and means to feed a substrate through the coating pot.

8. Apparatus as defined in claim 1, wherein said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of the metal body and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end along the length of one of said parallel arms in spaced relation, said one end of said lock fingers having a curved portion adapted to project into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock fingers, said release bar coupled to said lever means for rotating said lock fingers in unison to an open position upon said lever means being actuated by said trip means.

9. Apparatus as defined in claim 7, wherein each of said chutes includes two parallel guide rails extending along opposite sides of said ramp in a longitudinal direction, and wherein each of said clamp devices includes two roller members separated a distance slightly less than the distance separating said guide rails and adapted to ride on said ramps between said guide rails.

10. Apparatus as defined in claim 7, wherein said trip means comprises a pair of trip levers rotatably mounted at opposite sides of said ramp along its length and spring-biased upwardly so that the free ends of said trip levers are adapted to be rotated downwardly behind the surface of said ramp, and stop means to engage and hold said trip levers when their free ends rotate upwardly to a lever actuating position in front of said ramp, whereby said trip levers are rotated downwardly by engagement with said lever means as said clamp device is lowered and thereafter springs upwardly to said lever actuatinglposition.

. Apparatus as defined in claim 7, wherein said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of the metal body, a plurality of apertures formed in a straight line along the length of one of said parallel arms and a pivot rod fastened to the outside surface of said one parallel arm in a manner to extend across each of said plurality of apertures, and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end on said pivot rod in alignment with said plurality of apertures, said one end of said cam lock fingers having a curved portion adapted to project through said apertures into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock finger, said release bar coupled to said lever means for rotating said cam lock fingers in unison to an open position upon said lever means being actuated by said trip means.

12. Apparatus as defined in claim llll, wherein said lever means comprises a pair of dump bars pivotally mounted on said pivot rod, said dump bars having a first arm secured to said release bar and a second arm disposed in the path of said trip means. 

1. Apparatus for charging a metal body into a coating pot containing molten metal through which a substrate to be coated can be passed, said apparatus comprising a carriage assembly having at least one feeding chute, said feeding chute including a ramp extending transversely to the horizontal axis, means for moving said carriage assembly to position the lower end of said ramp above and adjacent to the coating pot, a clamp device adapted to ride up and down said ramp including a frame means for fitting over the edge of a metal body and lock means for releasably holding the metal body in said frame means, lever means carried by said frame means for opening said lock means to release the holding force on the metal body, and trip means carried by said chute and disposed in the path of said lever means for actuating said lever means to thereby open said lock means and release the holding force on the metal body, and means for raising and lowering said clamp device along the length of said ramp.
 2. Apparatus as defined in claim 1, wherein said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of the metal body and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end aLong the length of one of said parallel arms in a spaced relation, said one end of said lock fingers having a curved portion adapted to project into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock fingers, said release bar coupled to said lever means for rotating said lock fingers in unison to an open position upon said lever means being actuated by said trip means.
 3. Apparatus as defined in claim 1, wherein said chute includes two parallel guide rails extending along opposite sides of said ramp in a longitudinal direction, and wherein said clamp device includes two roller members separated a distance slightly less than the distance separating said guide rails and adapted to ride on said ramp between said guide rails.
 4. Apparatus as defined in claim 1, wherein said trip means comprises a pair of trip levers rotatably mounted at opposite sides of said ramp along its length and spring-biased upwardly so that the free ends of said trip levers are adapted to be rotated downwardly behind the surface of said ramp, and stop means to engage and hold said trip levers when their free ends rotate upwardly to a lever actuating position in front of said ramp, whereby said trip levers are rotated downwardly by engagement with said lever means as said clamp device is lowered and thereafter springs upwardly to said lever actuating position.
 5. Apparatus as defined in claim 1, where said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of a metal body, a plurality of apertures formed in a straight line along the length of one of said parallel arms and a pivot rod fastened to the outside surface of said one parallel arm in a manner to extend across each of said plurality of apertures, and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end on said pivot rod in alignment with said plurality of apertures, said one end of said cam lock fingers having a curved portion adapted to project through said apertures into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock fingers, said release bar coupled to said lever means for rotating said cam lock fingers in unison to an open position upon said lever means being actuated by said trip means.
 6. Apparatus as defined in claim 5, wherein said lever means comprises a pair of dump bars pivotally mounted on said pivot rod, said dump bars having a first arm secured to said release bar and a second arm disposed in the path of said trip means.
 7. Apparatus for charging a metal body into a coating pot containing molten metal through which a substrate to be coated is passed, said apparatus comprising a carriage assembly and a drive assembly, said carriage assembly comprising a radial framework forming a plurality of equally spaced chutes in a circular arrangement, each of said chutes including a ramp extending transversely to the horizontal axis, base means for rotatably supporting said radial framework such that the lower end of said ramps can be positioned above and adjacent to the coating pot, each of said chutes having a clamp device adapted to ride up and down said ramp and means for raising and lowering said clamp device along the length of said ramp, said clamp devices including frame means for fitting over the edge of a metal ingot and lock means for releasably holding the metal ingot in said frame means, lever means carried by said frame means for opening said lock means to release the holding force on the metal body trip means carried by each of said ramps and disposed in the path of said lever means for actuating said lever means to thereby open said lock means aNd release the holding force on the metal body, and means to feed a substrate through the coating pot.
 8. Apparatus as defined in claim 1, wherein said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of the metal body and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end along the length of one of said parallel arms in spaced relation, said one end of said lock fingers having a curved portion adapted to project into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock fingers, said release bar coupled to said lever means for rotating said lock fingers in unison to an open position upon said lever means being actuated by said trip means.
 9. Apparatus as defined in claim 7, wherein each of said chutes includes two parallel guide rails extending along opposite sides of said ramp in a longitudinal direction, and wherein each of said clamp devices includes two roller members separated a distance slightly less than the distance separating said guide rails and adapted to ride on said ramps between said guide rails.
 10. Apparatus as defined in claim 7, wherein said trip means comprises a pair of trip levers rotatably mounted at opposite sides of said ramp along its length and spring-biased upwardly so that the free ends of said trip levers are adapted to be rotated downwardly behind the surface of said ramp, and stop means to engage and hold said trip levers when their free ends rotate upwardly to a lever actuating position in front of said ramp, whereby said trip levers are rotated downwardly by engagement with said lever means as said clamp device is lowered and thereafter springs upwardly to said lever actuating position.
 11. Apparatus as defined in claim 7, wherein said frame means comprises an elongated U-shaped member having generally parallel arms separated a distance slightly greater than the thickness of the metal body, a plurality of apertures formed in a straight line along the length of one of said parallel arms and a pivot rod fastened to the outside surface of said one parallel arm in a manner to extend across each of said plurality of apertures, and wherein said lock means comprises a plurality of cam lock fingers rotatably mounted at one end on said pivot rod in alignment with said plurality of apertures, said one end of said cam lock fingers having a curved portion adapted to project through said apertures into the interior of said U-shaped member upon said lock finger being rotated to the locked position, and an elongated release bar extending the length of said U-shaped frame and joined to the other end of said cam lock finger, said release bar coupled to said lever means for rotating said cam lock fingers in unison to an open position upon said lever means being actuated by said trip means.
 12. Apparatus as defined in claim 11, wherein said lever means comprises a pair of dump bars pivotally mounted on said pivot rod, said dump bars having a first arm secured to said release bar and a second arm disposed in the path of said trip means. 